diff --git a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfig.java b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfig.java
index 67f1db2..d2460ac 100644
--- a/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfig.java
+++ b/drivers/fujitsu/src/main/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfig.java
@@ -16,6 +16,7 @@
 
 package org.onosproject.drivers.fujitsu;
 
+import com.google.common.collect.ImmutableSet;
 import org.onosproject.mastership.MastershipService;
 import org.onosproject.net.DeviceId;
 import org.onosproject.drivers.fujitsu.behaviour.VoltOnuOperConfig;
@@ -25,6 +26,7 @@
 import org.slf4j.Logger;
 
 import java.io.IOException;
+import java.util.Set;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static org.onosproject.drivers.fujitsu.FujitsuVoltXmlUtility.*;
@@ -41,10 +43,9 @@
     private static final String ONU_REBOOT = "onu-reboot";
     private static final String ONU_ETHPORT_LOOPBACK = "onu-ethport-loopback";
     private static final String ETHPORT_ID = "ethport-id";
-    private int pon;
-    private int onu;
-    private int eth;
-
+    private static final String LOOPBACK_MODE = "mode";
+    private static final Set<String> LOOPBACKMODES =
+            ImmutableSet.of("operate", "release");
 
     @Override
     public String rebootOnu(String target) {
@@ -60,39 +61,35 @@
             log.warn("Not master for {} Use {} to execute command",
                      ncDeviceId,
                      mastershipService.getMasterFor(ncDeviceId));
-            return reply;
+            return null;
         }
 
-        onuId = target.split(HYPHEN);
-        if (onuId.length != 2) {
-            log.error("Invalid number of arguments");
-            return reply;
-        }
-        try {
-            pon = Integer.parseInt(onuId[0]);
-            onu = Integer.parseInt(onuId[1]);
-        } catch (NumberFormatException e) {
-            log.error("Non-number input");
-            return reply;
+        onuId = checkIdString(target, TWO);
+        if (onuId == null) {
+            log.error("Invalid ONU identifier {}", target);
+            return null;
         }
 
         try {
             StringBuilder request = new StringBuilder();
-            request.append(ANGLE_LEFT).append(ONU_REBOOT).append(SPACE);
-            request.append(VOLT_NE_NAMESPACE).append(ANGLE_RIGHT).append(NEW_LINE);
-            request.append(buildStartTag(PONLINK_ID, false));
-            request.append(onuId[0]);
-            request.append(buildEndTag(PONLINK_ID));
-            request.append(buildStartTag(ONU_ID, false));
-            request.append(onuId[1]);
-            request.append(buildEndTag(ONU_ID));
-            request.append(buildEndTag(ONU_REBOOT));
+            request.append(ANGLE_LEFT + ONU_REBOOT + SPACE);
+            request.append(VOLT_NE_NAMESPACE + ANGLE_RIGHT + NEW_LINE);
 
-            reply = controller.
-                    getDevicesMap().get(ncDeviceId).getSession().
-                    doWrappedRpc(request.toString());
+            request.append(buildStartTag(PONLINK_ID, false))
+                .append(onuId[FIRST_PART])
+                .append(buildEndTag(PONLINK_ID))
+                .append(buildStartTag(ONU_ID, false))
+                .append(onuId[SECOND_PART])
+                .append(buildEndTag(ONU_ID))
+                .append(buildEndTag(ONU_REBOOT));
+
+            reply = controller
+                    .getDevicesMap()
+                    .get(ncDeviceId)
+                    .getSession()
+                    .doWrappedRpc(request.toString());
         } catch (IOException e) {
-            log.error("Cannot communicate to device {} exception ", ncDeviceId, e);
+            log.error("Cannot communicate to device {} exception {}", ncDeviceId, e);
         }
         return reply;
     }
@@ -105,51 +102,110 @@
         DeviceId ncDeviceId = handler.data().deviceId();
         checkNotNull(controller, "Netconf controller is null");
         String reply = null;
+        String[] data = null;
         String[] ethId = null;
 
         if (!mastershipService.isLocalMaster(ncDeviceId)) {
             log.warn("Not master for {} Use {} to execute command",
                      ncDeviceId,
                      mastershipService.getMasterFor(ncDeviceId));
-            return reply;
+            return null;
         }
 
-        ethId = target.split(HYPHEN);
-        if (ethId.length != 3) {
-            log.error("Invalid number of arguments");
-            return reply;
+        data = target.split(COLON);
+        if (data.length > TWO) {
+            log.error("Invalid number of parameters {}", target);
+            return null;
         }
-        try {
-            pon = Integer.parseInt(ethId[0]);
-            onu = Integer.parseInt(ethId[1]);
-            eth = Integer.parseInt(ethId[2]);
-        } catch (NumberFormatException e) {
-            log.error("Non-number input");
-            return reply;
+
+        ethId = checkIdString(data[FIRST_PART], THREE);
+        if (ethId == null) {
+            log.error("Invalid ETH port identifier {}", data[FIRST_PART]);
+            return null;
+        }
+
+        if (data.length > ONE) {
+            if (!LOOPBACKMODES.contains(data[SECOND_PART])) {
+                log.error("Unsupported parameter: {}", data[SECOND_PART]);
+                return null;
+            }
         }
 
         try {
             StringBuilder request = new StringBuilder();
-            request.append(ANGLE_LEFT).append(ONU_ETHPORT_LOOPBACK).append(SPACE);
-            request.append(VOLT_NE_NAMESPACE).append(ANGLE_RIGHT).append(NEW_LINE);
-            request.append(buildStartTag(PONLINK_ID, false));
-            request.append(ethId[0]);
-            request.append(buildEndTag(PONLINK_ID));
-            request.append(buildStartTag(ONU_ID, false));
-            request.append(ethId[1]);
-            request.append(buildEndTag(ONU_ID));
-            request.append(buildStartTag(ETHPORT_ID, false));
-            request.append(ethId[2]);
-            request.append(buildEndTag(ETHPORT_ID));
+            request.append(ANGLE_LEFT + ONU_ETHPORT_LOOPBACK + SPACE);
+            request.append(VOLT_NE_NAMESPACE + ANGLE_RIGHT + NEW_LINE);
+
+            request.append(buildStartTag(PONLINK_ID, false))
+                .append(ethId[FIRST_PART])
+                .append(buildEndTag(PONLINK_ID))
+                .append(buildStartTag(ONU_ID, false))
+                .append(ethId[SECOND_PART])
+                .append(buildEndTag(ONU_ID))
+                .append(buildStartTag(ETHPORT_ID, false))
+                .append(ethId[THIRD_PART])
+                .append(buildEndTag(ETHPORT_ID));
+            if (data.length > ONE) {
+                request.append(buildStartTag(LOOPBACK_MODE, false))
+                    .append(data[SECOND_PART])
+                    .append(buildEndTag(LOOPBACK_MODE));
+            }
             request.append(buildEndTag(ONU_ETHPORT_LOOPBACK));
 
-            reply = controller.
-                    getDevicesMap().get(ncDeviceId).getSession().
-                    doWrappedRpc(request.toString());
+            reply = controller
+                    .getDevicesMap()
+                    .get(ncDeviceId)
+                    .getSession()
+                    .doWrappedRpc(request.toString());
         } catch (IOException e) {
-            log.error("Cannot communicate to device {} exception ", ncDeviceId, e);
+            log.error("Cannot communicate to device {} exception {}", ncDeviceId, e);
         }
         return reply;
     }
 
+    /**
+     * Verifies input string for ponlink-id{-onu-id}{-ethport-id}.
+     *
+     * @param target input data in string
+     * @param expected number of IDs expected
+     * @return String array containing IDs; may be null if an error is detected
+     */
+    private String[] checkIdString(String target, int expected) {
+        String[] id = target.split(HYPHEN);
+        int pon;
+        int onu;
+
+        if (id.length < TWO) {
+            log.error("Invalid number of arguments for id: {}", id.length);
+            return null;
+        }
+        if (id.length != expected) {
+            log.error("Invalid number of arguments for id: {}", id.length);
+            return null;
+        }
+        try {
+            pon = Integer.parseInt(id[FIRST_PART]);
+            if (pon <= ZERO) {
+                log.error("Invalid integer for ponlink-id: {}", id[FIRST_PART]);
+                return null;
+            }
+            onu = Integer.parseInt(id[SECOND_PART]);
+            if (onu <= ZERO) {
+                log.error("Invalid integer for onu-id: {}", id[SECOND_PART]);
+                return null;
+            }
+            if (expected > TWO) {
+                int port = Integer.parseInt(id[THIRD_PART]);
+                if (port <= ZERO) {
+                    log.error("Invalid integer for port-id: {}", id[THIRD_PART]);
+                    return null;
+                }
+            }
+        } catch (NumberFormatException e) {
+            log.error("Non-number input for id: {}", target);
+            return null;
+        }
+        return id;
+    }
+
 }
diff --git a/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfigTest.java b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfigTest.java
new file mode 100644
index 0000000..b6bf0de
--- /dev/null
+++ b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltOnuOperConfigTest.java
@@ -0,0 +1,279 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.drivers.fujitsu;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertNotNull;
+import static org.onosproject.drivers.fujitsu.FujitsuVoltXmlUtilityMock.*;
+
+/**
+ * Unit tests for methods of FujitsuVoltOnuOperConfig.
+ */
+public class FujitsuVoltOnuOperConfigTest {
+
+    private final FujitsuNetconfSessionListenerTest listener = new InternalSessionListener();
+
+    private static final String TEST_ONU_REBOOT = "onu-reboot";
+    private static final String TEST_ONU_ETHPORT_LOOPBACK = "onu-ethport-loopback";
+    private static final String TEST_ETHPORT_ID = "ethport-id";
+    private static final String TEST_LOOPBACK_MODE = "mode";
+
+    private static final String TEST_ONU_REBOOT_WITH_NAMESPACE = TEST_ANGLE_LEFT +
+            TEST_ONU_REBOOT + TEST_SPACE + TEST_VOLT_NE_NAMESPACE;
+    private static final String TEST_ONU_ETHPORT_LOOPBACK_WITH_NAMESPACE =
+            TEST_ANGLE_LEFT + TEST_ONU_ETHPORT_LOOPBACK + TEST_SPACE +
+            TEST_VOLT_NE_NAMESPACE;
+
+    private static final String[] INVALID_REBOOT_TCS = {
+        "xy1-b",
+        "--1",
+        "s-1",
+        "16-1-1",
+        "&AA-1",
+        "-1-1",
+    };
+    private static final String[] VALID_REBOOT_TCS = {
+        "1-2",
+        "16-11",
+    };
+    private static final String[] INVALID_ETHPORT_LOOPBACK_TCS = {
+        "-11-3--11",
+        "1-CCa",
+        "abc-1",
+        "^1-1-3",
+        "1-2:23-1",
+        "1:33:2",
+        "2-2-2:false",
+    };
+    private static final String[] VALID_ETHPORT_LOOPBACK_TCS = {
+        "8-1-1",
+        "1-11-3:release",
+        "2-2-2:operate",
+    };
+    private Integer currentKey;
+    private FujitsuNetconfControllerMock controller;
+    private FujitsuDriverHandlerAdapter driverHandler;
+    private FujitsuVoltOnuOperConfig voltConfig;
+
+    @Before
+    public void setUp() throws Exception {
+        controller = new FujitsuNetconfControllerMock();
+        driverHandler = controller.setUp(listener);
+        voltConfig = new FujitsuVoltOnuOperConfig();
+        voltConfig.setHandler(driverHandler);
+    }
+
+    /**
+     * Run to verify handling of invalid input for rpc operation.
+     */
+    @Test
+    public void testInvalidRebootOnuInput() throws Exception {
+        String reply;
+        String target;
+
+        for (int i = ZERO; i < INVALID_REBOOT_TCS.length; i++) {
+            target = INVALID_REBOOT_TCS[i];
+            reply = voltConfig.rebootOnu(target);
+            assertNull("Incorrect response for INVALID_REBOOT_TCS", reply);
+        }
+    }
+
+    /**
+     * Run to verify handling of valid input for rpc operation.
+     */
+    @Test
+    public void testValidRebootOnu() throws Exception {
+        String reply;
+        String target;
+
+        for (int i = ZERO; i < VALID_REBOOT_TCS.length; i++) {
+            target = VALID_REBOOT_TCS[i];
+            currentKey = i;
+            reply = voltConfig.rebootOnu(target);
+            assertNotNull("Incorrect response for VALID_REBOOT_TCS", reply);
+        }
+    }
+
+    /**
+     * Run to verify handling of invalid input for rpc operation.
+     */
+    @Test
+    public void testInvalidEthLoopbackOnuInput() throws Exception {
+        String target;
+        String reply;
+
+        for (int i = ZERO; i < INVALID_ETHPORT_LOOPBACK_TCS.length; i++) {
+            target = INVALID_ETHPORT_LOOPBACK_TCS[i];
+            reply = voltConfig.loopbackEthOnu(target);
+            assertNull("Incorrect response for INVALID_ETHPORT_LOOPBACK_TCS", reply);
+        }
+    }
+
+    /**
+     * Run to verify handling of valid input for rpc operation.
+     */
+    @Test
+    public void testValidLoopbackEthOnu() throws Exception {
+        String target;
+        String reply;
+
+        for (int i = ZERO; i < VALID_ETHPORT_LOOPBACK_TCS.length; i++) {
+            target = VALID_ETHPORT_LOOPBACK_TCS[i];
+            currentKey = i;
+            reply = voltConfig.loopbackEthOnu(target);
+            assertNotNull("Incorrect response for VALID_ETHPORT_LOOPBACK_TCS", reply);
+        }
+    }
+
+    /**
+     * Verifies XML request string by comparing with generated string.
+     *
+     * @param request XML string for rpc operation
+     * @return true or false
+     */
+    private boolean verifyWrappedRpcRequestForReboot(String request) {
+        StringBuilder rpc = new StringBuilder();
+        String target = VALID_REBOOT_TCS[currentKey];
+        String[] data = target.split(TEST_COLON);
+        String[] onuId = data[FIRST_PART].split(TEST_HYPHEN);
+
+        rpc.append(TEST_ANGLE_LEFT + TEST_ONU_REBOOT + TEST_SPACE);
+        rpc.append(TEST_VOLT_NE_NAMESPACE + TEST_ANGLE_RIGHT + TEST_NEW_LINE);
+
+        rpc.append(startTag(TEST_PONLINK_ID, false))
+            .append(onuId[FIRST_PART])
+            .append(endTag(TEST_PONLINK_ID))
+            .append(startTag(TEST_ONU_ID, false))
+            .append(onuId[SECOND_PART])
+            .append(endTag(TEST_ONU_ID))
+            .append(endTag(TEST_ONU_REBOOT));
+
+        String testRequest = rpc.toString();
+        String regex = TEST_WHITESPACES_REGEX;
+        int index = rpc.indexOf(regex);
+        while (index >= ZERO) {
+            testRequest = rpc.replace(index, index + regex.length(), TEST_EMPTY_STRING).toString();
+            request = request.replaceAll(regex, TEST_EMPTY_STRING);
+        }
+        boolean result = request.equals(testRequest);
+        assertTrue("Does not match with generated string", result);
+        return result;
+    }
+
+    /**
+     * Verifies XML request string by comparing with generated string.
+     *
+     * @param request XML string for rpc operation
+     * @return true or false
+     */
+    private boolean verifyWrappedRpcRequestForEthLoopback(String request) {
+        StringBuilder rpc = new StringBuilder();
+        String target = VALID_ETHPORT_LOOPBACK_TCS[currentKey];
+        String[] data = target.split(TEST_COLON);
+        String[] ethId = data[FIRST_PART].split(TEST_HYPHEN);
+
+        rpc.append(TEST_ANGLE_LEFT + TEST_ONU_ETHPORT_LOOPBACK + TEST_SPACE);
+        rpc.append(TEST_VOLT_NE_NAMESPACE + TEST_ANGLE_RIGHT + TEST_NEW_LINE);
+
+        rpc.append(startTag(TEST_PONLINK_ID, false))
+            .append(ethId[FIRST_PART])
+            .append(endTag(TEST_PONLINK_ID))
+            .append(startTag(TEST_ONU_ID, false))
+            .append(ethId[SECOND_PART])
+            .append(endTag(TEST_ONU_ID))
+            .append(startTag(TEST_ETHPORT_ID, false))
+            .append(ethId[THIRD_PART])
+            .append(endTag(TEST_ETHPORT_ID));
+        if (data.length > SECOND_PART) {
+            rpc.append(startTag(TEST_LOOPBACK_MODE, false))
+                .append(data[SECOND_PART])
+                .append(endTag(TEST_LOOPBACK_MODE));
+        }
+        rpc.append(endTag(TEST_ONU_ETHPORT_LOOPBACK));
+
+        String testRequest = rpc.toString();
+        String regex = TEST_WHITESPACES_REGEX;
+        int index = rpc.indexOf(regex);
+        while (index >= ZERO) {
+            testRequest = rpc.replace(index, index + regex.length(), TEST_EMPTY_STRING).toString();
+            request = request.replaceAll(regex, TEST_EMPTY_STRING);
+        }
+        boolean result = request.equals(testRequest);
+        assertTrue("Does not match with generated string", result);
+        return result;
+    }
+
+    /**
+     * Internal listener for device service events.
+     */
+    private class InternalSessionListener implements FujitsuNetconfSessionListenerTest {
+        @Override
+        public boolean verifyEditConfig(String request) {
+            return false;
+        }
+
+        @Override
+        public boolean verifyEditConfig(String target, String mode, String request) {
+            return false;
+        }
+
+        @Override
+        public boolean verifyGet(String filterSchema, String withDefaultsMode) {
+            return false;
+        }
+
+        @Override
+        public String buildGetReply() {
+            return null;
+        }
+
+        @Override
+        public boolean verifyWrappedRpc(String request) {
+            boolean result;
+            boolean reboot = false;
+
+            if (request.contains(TEST_ONU_REBOOT)) {
+                request = request.replaceAll(TEST_DUPLICATE_SPACES_REGEX, TEST_SPACE);
+                assertTrue("Does not contain:" + TEST_ONU_REBOOT_WITH_NAMESPACE,
+                        request.contains(TEST_ONU_REBOOT_WITH_NAMESPACE));
+                reboot = true;
+            } else {
+                request = request.replaceAll(TEST_DUPLICATE_SPACES_REGEX, TEST_SPACE);
+                assertTrue("Does not contain:" + TEST_ONU_ETHPORT_LOOPBACK_WITH_NAMESPACE,
+                        request.contains(TEST_ONU_ETHPORT_LOOPBACK_WITH_NAMESPACE));
+            }
+
+            if (reboot) {
+                result = verifyWrappedRpcRequestForReboot(request);
+            } else {
+                result = verifyWrappedRpcRequestForEthLoopback(request);
+            }
+
+            assertTrue("XML verification failure", result);
+            return result;
+        }
+
+        @Override
+        public void verifyStartSubscription(String filterSchema) {
+        }
+    }
+
+}
diff --git a/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltXmlUtilityMock.java b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltXmlUtilityMock.java
index e9200a3..19a6981 100644
--- a/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltXmlUtilityMock.java
+++ b/drivers/fujitsu/src/test/java/org/onosproject/drivers/fujitsu/FujitsuVoltXmlUtilityMock.java
@@ -58,6 +58,7 @@
     public static final int FIRST_PART = 0;
     public static final int SECOND_PART = 1;
     public static final int THIRD_PART = 2;
+    public static final int ZERO = 0;
     public static final int ONE = 1;
 
     private FujitsuVoltXmlUtilityMock() {